1. Technical Field
The present invention relates generally to technology for configuring and controlling the taillight of a vehicle and, more particularly, to a method of controlling a taillight which is capable of integrating the function of a sidelight indicative of the presence and width of a vehicle ahead of the driver, especially, during nighttime driving, and the function of a brake light operative to be automatically turned on when a driver steps on the brake of the vehicle and then providing the integrated function, and which is also capable of providing information about the operation of a vehicle to a following vehicle via visible light wireless communication.
2. Description of the Related Art
Recently, lights and display devices using light-emitting diodes (LEDs) have rapidly spread into products for daily life, such as vehicles, traffic lights, billboards, TVs, monitors, mobile devices, special lighting and common lighting. The reason for this is that LED light sources have a longer lifespan, exhibit excellent power efficiency, facilitate digital control, and implement various colors, compared to existing light sources, such as fluorescent lamps or incandescent lamps. Furthermore, active research has been carried out into visible light wireless communication technology that adds communication functionality to LED lights and display devices, thereby achieving both the unique purpose of an LED light source and the purpose of a communication means.
Visible light wireless communication technology is communication technology that wirelessly transfers information using visible light in the wavelength range from 380 nm to 780 nm which is visible to the human eye. This technology is distinguished from existing wired optical communication technology and wireless infrared light communication technology using the infrared wavelength band in that this technology uses light in the visible ray wavelength band.
Unlike radio frequency (RF) wireless communication now being widely used, visible light wireless communication technology can be freely used without any regulations or permission in terms of a frequency use. Furthermore, visible light wireless communication technology is different from RF wireless communication in that it has excellent physical security and a communication link can be checked by a user's eye. Furthermore, visible light wireless communication technology has a convergence technology characteristic that enables both the unique purpose of a light source and communication functionality to be achieved.
Such visible light wireless communication technology includes variable pulse position modulation (VPPM) technology that is capable of performing both a modulation function for sending visible light wireless communication data and a function for controlling the brightness of a lighting source using LED lighting. In this technology, the bit “1” or “0” is represented depending on whether a pulse section in which a light source is turned on is located in the front or rear part of a unit symbol section, and the brightness of the light source can be changed by changing the temporal length of a pulse section in which the light source is turned on.
The brightness of LED lighting may be basically controlled using two methods. One of the two methods is a method of changing the amount of voltage or current applied to an LED light source via an analog circuit, and the other of the two methods is a pulse width modulation (PWM) method of controlling the time during which an LED light source remains turned along a time axis through digital control. In the above-described VPPM modulation technology, the brightness of a light source is controlled using the PWM method.
Each of the existing taillights of a vehicle usually includes two lamps. A sidelight and a brake light are mounted in a single frame and thus form the taillight. In general, the turning on and off of the sidelight is manually controlled by a driver, and the brake light is controlled so that it is turned on when a driver steps on a deceleration pedal in order to reduce the speed of a vehicle. Furthermore, the conventional sidelight and brake light of a vehicle are detected by only the visual perception of a driver who drives a following vehicle, but do not have the function for transmitting data from the sidelight or brake light of the preceding vehicle to a following vehicle via visible light wireless communication.
The conventional taillight of a vehicle is manually turned on or off by a driver. Accordingly, a problem arises in that a following vehicle may become endangered if the taillight of a preceding vehicle is not turned on in nighttime driving, or in that the battery of a vehicle may continue to be consumed because a driver does not turn off a taillight upon parking. Furthermore, it is difficult to provide light of a brightness optimized in proportion to external illumination because the brightness of the taillight is always maintained at a uniform level.
With the rapid replacement of conventional lamps with LED lamps in taillights mounted on various types of vehicles, there is an increasing need for convergence technology including wireless communication functionality using LED lamps and brightness control technology reflecting the characteristics of LED lamps.
As related art, Korean Patent Application Publication No. 10-2009-0001105 discloses an LED lamp for the combined brake and tail light of an automobile.